The point is it's less far than it looks (humans are bad at judging vertical distances), and giving a real-world comparison makes the real height easier to conceptualize than an abstract number.
Humans are also bad at comparing horizontal differences to vertical ones. Switching from one to the other obscures the difficulty of going higher. If the peak of Everest were 8,848 meters in distance rather than height, it would be an unremarkable hike.
That makes sense; it's easier to take a horizontal step than a vertical one. Someone should do up an infographic showing the effect of gravity on work required for horizontal versus vertical movement.
